1. Field of the Invention
The invention relates generally to an increased I/O lead frame and a semiconductor device incorporating the same.
2. Description of the Related Art
Generally, a lead frame for a semiconductor device is fabricated by mechanical stamping or chemical etching of metal strips. The lead frame serves to connect a semiconductor die to an external circuit and fix the semiconductor device to an external device, simultaneously.
The lead frame for the semiconductor device is generally a copper based (copper:iron:phosphorous=99.8:0.01:0.025) lead frame, a copper alloy based (copper:chrome:solder:zinc=99:0.25:0.25:0.22) lead frame, an alloy-42 based (iron:nickel=58:42) lead frame, in addition to others. The semiconductor devices using the lead frames include a through-hole mounting type dual inline package (DIP), a surface mounting type quad flat package (QFP) having smaller size and higher electrical performance, a small outline package (SOP), in addition to others.
However, in many semiconductor devices, leads of the semiconductor device are projected outwardly through a side portion of an encapsulant at a constant length. As a result, the size of the semiconductor device becomes larger and the number of input/output pins becomes smaller. In other words, though a semiconductor die may need a large number of input/output pins due to high integration and high functionality, it is difficult for the lead frame to satisfy the need of the semiconductor die.
Accordingly, in order to solve the problem, a ball grid array (BGA) or a pin grid array (PGA) semiconductor device using a laminate circuit substrate, a tape circuit substrate or a film circuit substrate has been developed in the prior art. A plurality of solder balls or metal pins of the semiconductor device are area-arrayed not in a side portion of the encapsulant, but rather in a lower portion of the encapsulant (e.g. a lower portion of a circuit substrate). As a result, a relatively large number of input/output pins can be provided.
However, the semiconductor device has high-priced circuit substrate. Additionally, heatproof performance and electrical performance of the semiconductor device are deteriorated, in comparison with a semiconductor device using a lead frame. In other words, a semiconductor die of the semiconductor device using a lead frame is often directly mounted on a die pad made of a copper material. Additionally, electric performance of semiconductor device can be improved due to high heatproof performance. However, it is difficult for the above-described semiconductor device using the circuit substrate to have the structure of the semiconductor device using the lead frame.